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Marine Policy 36 (2012) 307–320
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Marine Policy
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Sustainability of deep-sea fisheries
Elliott A. Norse a,n, Sandra Brooke a, William W.L. Cheung b, Malcolm R. Clark c, Ivar Ekeland d,
Rainer Froese e, Kristina M. Gjerde f, Richard L. Haedrich g, Selina S. Heppell h, Telmo Morato i,j,
Lance E. Morgan k, Daniel Pauly l, Rashid Sumaila l, Reg Watson l
a
Marine Conservation Institute, 2122 112th Ave NE, Suite B-300, Bellevue WA 98004, USA
School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK
c
National Institute of Water & Atmospheric Research (NIWA), Evans Bay Parade, Wellington 6021, New Zealand
d
Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver BC, Canada V6T 1Z2
e
Leibniz-Institute of Marine Sciences, IFM-GEOMAR, Düsternbrooker Weg 20, 24105 Kiel, Germany
f
IUCN Global Marine Programme, Rue Mauverney 28, 1196 Gland, Switzerland
g
Memorial University, 53 Beaver Meadow Road, Norwich, VT 05055, USA
h
Fisheries and Wildlife, Oregon State University, 104 Nash Hall, Corvallis OR 97330, USA
i
Departmento de Oceanografia e Pescas, Universidade dos Ac- ores, 9901-862 Horta, Portugal
j
Oceanic Fisheries Program, Secretariat of the Pacific Community, Noumea, New Caledonia
k
Marine Conservation Institute, 14301 Arnold Drive, Suite 25, Glen Ellen CA 95442, USA
l
Fisheries Centre, 2202 Main Mall, University of British Columbia, Vancouver BC, Canada, V6T 1Z4
b
a r t i c l e i n f o
abstract
Article history:
Received 17 May 2011
Received in revised form
24 June 2011
Accepted 25 June 2011
As coastal fisheries around the world have collapsed, industrial fishing has spread seaward and deeper
in pursuit of the last economically attractive concentrations of fishable biomass. For a seafood-hungry
world depending on the oceans’ ecosystem services, it is crucial to know whether deep-sea fisheries can
be sustainable.
The deep sea is by far the largest but least productive part of the oceans, although in very limited
places fish biomass can be very high. Most deep-sea fishes have life histories giving them far less
population resilience/productivity than shallow-water fishes, and could be fished sustainably only at
very low catch rates if population resilience were the sole consideration. But like old-growth trees and
great whales, their biomass makes them tempting targets while their low productivity creates strong
economic incentive to liquidate their populations rather than exploiting them sustainably (Clark’s Law).
Many deep-sea fisheries use bottom trawls, which often have high impacts on nontarget fishes
(e.g., sharks) and invertebrates (e.g., corals), and can often proceed only because they receive massive
government subsidies. The combination of very low target population productivity, nonselective fishing
gear, economics that favor population liquidation and a very weak regulatory regime makes deep-sea
fisheries unsustainable with very few exceptions. Rather, deep-sea fisheries more closely resemble
mining operations that serially eliminate fishable populations and move on.
Instead of mining fish from the least-suitable places on Earth, an ecologically and economically
preferable strategy would be rebuilding and sustainably fishing resilient populations in the most
suitable places, namely shallower and more productive marine ecosystems that are closer to markets.
& 2011 Published by Elsevier Ltd.
Keywords:
Sustainability
Deep-sea fisheries
Fishery collapse
Fisheries economics
Clark’s law
High seas
1. Introduction
Fishing has profoundly changed the distribution of fishes and
fisheries worldwide, and is now occurring deep in the world’s
oceans far from fishing ports and consumers. These changes
compel us to examine whether deep-sea fisheries can be
sustainable.
n
Corresponding author. Tel.: þ1 425 968 0449; fax: þ1 425 274 1183.
E-mail address: [email protected] (E.A. Norse).
0308-597X/$ - see front matter & 2011 Published by Elsevier Ltd.
doi:10.1016/j.marpol.2011.06.008
It is difficult to appreciate how abundant marine life was in
the past because people keep reducing expectations as we forget
former conditions [1]. But the evidence is unmistakable. After
reaching Labrador in 1508, Sebastian Cabot reported Atlantic
cod (Gadus morhua, Gadidae) abundant enough to impede his
ships’ progress; two centuries later, Pierre de Charlevoix equated
numbers of Grand Banks cod to grains of sand, calling
cod fisheries ‘‘mines’’ more valuable than the mines of Peru
and Mexico [2]. Many coastal ecosystems were phenomenally
bountiful [3] until people impoverished them long ago [4].
Severe widespread depletion of large fishes in continental shelf
308
E.A. Norse et al. / Marine Policy 36 (2012) 307–320
waters [2] and in oceanic epipelagic ecosystems [5] was much
more recent.
While increasing human population and affluence have raised
global demand for fish, increasing scarcity of continental shelf and
epipelagic oceanic fishes has driven industrial fishing farther from
home ports and markets and to depths that were not even
believed to host life until the 1800s. Global marine fisheries
catches, as reported by fishing countries to the United Nations
Food and Agriculture Organization (FAO), have stagnated at about
90 million metric tons since the late 1990s, and have declined
since the late 1980s if the doubtful figures reported by China are
excluded [6,7]. The large catch increase of the 1960s and 1970s
was largely due the seaward and southward expansion of industrial (notably trawl) fisheries from waters along the coasts of
developed countries of the Northern Hemisphere. When this
expansion ended – in Antarctic waters – catches could increase
only by fishing in deeper waters [8,9].
Scientists with expertise on fishes, fisheries and deep-sea
biology question whether deep-sea fisheries can be sustainable
[9–19]. A sound answer depends on but transcends ecology,
taking ocean policy makers into the realms of economics and law.
Despite sharing an Ancient Greek root (oikos, meaning household), ecology and economics have diverged in their world views,
often leading their practitioners to differing strategies for managing our collective household, the biosphere, including the 99% of
its volume that is ocean. But there are fundamental similarities
between ecology and economics. In fisheries it is commonplace to
call populations ‘‘stocks,’’ alluding to their similarity to capital
stocks in economics. Central to this paper is the analogy between
(a) the biomass of fish stocks and the productivity they generate,
with (b) capital stocks (principal) and the dividends (or interest)
they generate. With deep-sea fisheries as our focus, this paper
examines what the authors are calling Clark’s Law, the seminal
connection between the ecological and economic determinants of
sustainability as first explained in Clark [20,21]. Using comparable metrics and combining insights and the evidence from
fisheries, ecology, economics and international ocean governance,
this paper examines whether deep-sea fisheries can be sustainable. Governments and international governing organizations
need to know this because maintaining biodiversity in the deep
sea is crucial to biogeochemistry on a global scale, and hence to
humankind [22,23].
2. Fishing deeper
Commercial fishing is occurring at increasing depths around
the globe. Based on readily available catch data series and fish life
history parameters, Morato et al. [24] showed that marine fisheries worldwide have operated at increased depths since the
1970s. In the high seas (i.e. beyond countries’ exclusive economic
zones, EEZs), the increasing depth of fishing was more dramatic,
some 250 m. They based this inference on the relative increase in
the global catch of species (or higher taxa) known to occur in deeper
waters, which have increased 7-fold since the mid-1960s [25]. As
fisheries operated farther offshore and deeper, exploiting increasing portions of the ranges of marine species [26,27], they also
exploited the deeper part of these species’ ranges. Accounting for
this effect increases the mean depth of fisheries catches more
than 4-fold.1
These studies show that fisheries are overexploiting both the
last refuges for many fish species and species with less resilience
[28,29], a point we examine in the following two sections.
1
T. Morato, R. Watson and D. Pauly, unpublished data.
3. Productivity of the deep sea
Once considered a vast cornucopia for a hungry world, the
productivity of most of the open ocean is more akin to a watery
desert. Ryther [30] was one of the first to quantify the scarcity of
production to support large deep-sea fisheries. Using measurements of primary productivity and simple ecological rules about
food chain trophic efficiency, he calculated that continental shelf
fisheries in the western North Atlantic were unsustainable. Little
attention was paid to his conclusion, however, and what had
essentially become a fish-mining operation took 30 years to
collapse. Shelf fisheries elsewhere also declined, so by 1999, 40%
of the world’s major trawling grounds had shifted offshore
[12,31].
Relatively little primary production per unit area occurs in
most of the oceanic epipelagic zone, and its food energy may pass
through several trophic levels as it sinks, with a rapid decline in
biomass before reaching the benthos. This varies, however, with
season and region, and recent work is increasing our understanding of flux of production from the surface to the seafloor
[32]. Nonetheless, the combination of low epipelagic productivity
and high rates of loss in the water column with increasing depth
makes the vast majority of oceanic seafloor energy- and nutrientscarce.
Much of the deep ocean is seemingly featureless (but, in
places, species-rich) mud punctuated by isolated ‘‘oases’’ of high
biomass supporting a diverse benthic and demersal fauna. Hydrothermal vents and cold seeps that rely on chemosynthetic
primary production apparently have little or no interest for
fisheries, but topographic features such as seamounts, mid-ocean
ridges, banks, continental slopes and canyons can support commercially valuable species because these features modify the
physical and biological dynamics in ways that enhance and retain
food delivery [33,34]. Some commercially targeted species form
dense breeding aggregations over deep-sea structures, further
increasing biomass concentrations, allowing large catches over
some seamounts.
Rowe et al. [35] calculated that a bottom fishery in 100 km2 of
the deep central Pacific would produce no more than 200 kg
annually, a minuscule quantity compared to the 8000 t of orange
roughy (Hoplostethus atlanticus, Trachichthyidae) caught on average each year over the 30 years of that fishery [36]. Therefore, the
success of large-scale deepwater fisheries depends upon regionalor local-scale production processes. This emphasizes, at very
least, the need for site-specific information and a precautionary
approach as the footprint of fisheries expands.
In the deep sea, despite the apparent higher levels of productivity over seamounts and similar features, species cannot support high levels of exploitation. Fishing on spawning aggregations
has rapidly depleted even shallow-water fishes [12], and life
history characteristics of deep-sea species magnify their vulnerability. Many deep-sea trawl fisheries show a serial pattern of
‘‘boom and bust,’’ as we show in later sections.
4. Life histories and population resilience of deep-sea fishes
Deep-sea fishes show remarkable adaptations to life in a cold,
dark, low-productivity environment [37]. Depth and temperature
directly affect fish growth rates, which tie to a range of life history
characteristics that affect the maximum intrinsic population
growth rate (rmax) [38,39], including delayed maturity, high
maximum age and low average productivity [24,40–44]. Low fish
stock productivity, in turn, affects the capacity of those species to
respond to fishing pressure and tightly restricts the maximum
catch that a population can tolerate [45].
E.A. Norse et al. / Marine Policy 36 (2012) 307–320
species. Seamounts cover a broad depth range and host some
species that may not qualify as true ‘‘deep-sea’’ fishes, yet even
these include very few species having ‘‘highly resilient’’ characteristics. While these resilience ratings are based on preliminary
estimates or characteristics for many species, they are generated
through well-established empirical relationships observed in
shallow-water species and suggest that deep-sea environments
do constrain productivity in many deep-sea fishes.
Generally, a species’ resilience is directly linked to its intrinsic
rate of population increase (rmax), which is a function of the vital
rates affecting births and deaths in the population [52,57].
Populations with lower rmax are less productive and will have
slower recovery from fishing mortality [47]. While low-productivity stocks should be able to cope with very low fishing
pressure, the maximum exploitation rate they can tolerate may
fall below key economic rates, threatening the population. Intrinsic vulnerability to fishing is calculated from a fuzzy logic expert
system that incorporates known relationships between life history and ecological characteristics of a species or population and
their intrinsic vulnerability to fishing [55]. The index requires one
or more of the following data: maximum body length, age at
maturity, longevity, von Bertalanffy growth parameter K, natural
mortality rate, fecundity and fish’s behavior in forming aggregations. Such information is available through online databases
(e.g., FishBase). The intrinsic vulnerability index scales from 1 to
100, with 100 being most vulnerable to fishing.
Authors of this paper compiled and calculated various metrics
of resilience and intrinsic vulnerability to fishing of a range of
deep-sea fishes for which some biological information could be
obtained. The list is restricted to species deeper than 200 m and
which had either maximum age or growth data available
in FishBase [56]. In this list, the authors excluded deep-sea fishes
from the Mediterranean Sea because its temperature at depth is
exceptionally warm ( 413 1C), atypical for deep-sea habitats [58].
The authors also included examples of FAO’s [59] major deep-sea
fishery species, which may sometimes occur in shallower waters
( o200 m depth) but are well-represented in deep-sea fisheries
(Table 1).
The data required for calculating rmax using conventional
methods such as life table analysis [60] are not available for many
deep-sea fishes. Therefore the authors used empirical relationships to estimate rmax. The authors assumed that rmax ¼2 M [61],
Delayed maturity and low or episodic recruitment are common traits in many overexploited fish stocks worldwide [46–48].
Due to cold temperatures and high variance in food resources,
most deep-sea fishes grow slowly, although species vary in
allocation of their reproductive investment (large or small eggs,
reproducing often or rarely), likely in response to the environmental variance experienced by their offspring. Many deep-sea
species have larger eggs and hence lower fecundity than other
teleosts of similar size [49]. Greater yolk reserves for the developing larva may be an adaptation to food limitation.
Although some deep-sea fishes are highly fecund, they seem to
have characteristics of ‘‘periodic strategists’’ [41], namely long
lifespans to accommodate extremely variable early survival. This
strategy is often accompanied by high variance in recruitment
success and spawning frequencies less than once per year [50,51],
leading to resilience too low to compensate for high adult
mortality.
At first it might seem that high fecundity leads to greater
average population resilience, but empirical evaluation of many
taxa indicate that more fecund fishes do not show higher
recruitment or faster recovery rates than species with fewer
offspring per year [45,46,52,53]. Life table analysis of two highly
fecund North Atlantic grenadier species suggests very slow
response to exploitation and potential for multi-decadal recovery
times [29]. Two overfished stocks of very long-lived North Pacific
rockfishes (genus Sebastes, Sebastidae) are currently on recovery
plans that span several decades, in spite of fecundity estimates in
the hundreds of thousands of larvae per female [54].
Are deep-sea fishes less resilient, on average, than those in
shallow marine ecosystems? Resilience (and its opposite, intrinsic
vulnerability) reflects the capacity of a species or population to
tolerate impacts without irreversible change in its population
structure [55,56], which are tightly linked to its life history.
Because temperature and ecosystem productivity are related to
species’ growth, one can generally predict a resilience ‘‘score’’ for
any species based on limited biological information.
For species with either growth rate or fecundity estimates
(or both) documented in FishBase, a much smaller proportion
receive a ‘‘highly resilient’’ ranking (high growth rates, small body
size and/or high fecundity per body mass) among bathypelagic,
bathydemersal, and seamount species (Fig. 1), and a higher
proportion of these are therefore ‘‘low’’ and ‘‘very low’’ resilience
High
Medium
Low
309
Very Low
100
90
Resilient Species (%)
80
70
60
50
40
30
20
10
0
pelagic
(N = 1686)
demersal
(N = 8938)
bathypelagic
(N = 448)
bathydemersal
(N = 1880)
seamount
(N = 513)
Fig. 1. Predicted resilience for fishes in different marine habitats from species entries in FishBase [56]. Resilience is defined by expected population doubling time and
ability to compensate for a threshold level of biomass reduction within 10 years or 3 generations [147], based on observed values (rarely available for deep-sea fishes)
or on empirical relationships between maximum productivity and age at maturity, lifespan, the von Bertalanffy age-length growth parameter K, and fecundity.
310
E.A. Norse et al. / Marine Policy 36 (2012) 307–320
Table 1
Life history, maximum population growth rate (rmax) and intrinsic vulnerability index of 41 species of deep-sea fishes, those typically found deeper than 200 m and which
had either maximum age or growth data available in FishBase [56]. The Table also includes examples of species exploited by deep-sea fisheries and commercially
important non deep-sea fish that have available estimates of longevity or von Bertalanffy growth parameter K in FishBase [59]. Maximum body length (Lmax) is represented
by total length. rmax is calculated from the approximations rmax E 2 M E3 K. (R. Froese unpublished data; see text). M is estimated from Hoenig’s [61] empirical
equation based on observed maximum age. If no maximum age was known, we used the von Bertalanffy growth parameter K and followed Jensen’s [55] suggested
approximation with M ¼3/2 K. Intrinsic vulnerability index is calculated using the method by [62].
Family
Scientific name
Common name
Deep-sea fishes
Alepocephalidae
Alepocephalidae
Epigonidae
Etmopteridae
Alepocephalus bairdii
Alepocephalus rostratus
Epigonus elegans
Etmopterus baxteri
Lophiidae
Macrouridae
Macrouridae
Macrouridae
Neoscopelidae
Rajidae
Sebastidae
Somniosidae
Somniosidae
Trachipteridae
Lophius budegassa
Coryphaenoides acrolepis
Coryphaenoides longifilis
Nezumia stelgidolepis
Scopelengys tristis
Bathyraja trachura
Sebastolobus altivelis
Centroselachus crepidater
Proscymnodon plunketi
Trachipterus arcticus
Baird’s smooth-head
Risso’s smooth-head
–
New Zealand
lanternshark
Black-bellied angler
Pacific grenadier
Longfin grenadier
California grenadier
Pacific blackchin
Roughtail skate
Longspine thornyhead
Longnose velvet dogfish
Plunket shark
Dealfish
Deep-sea exploited fishes
Anoplopomatidae
Anoplopoma fimbria
Berycidae
Beryx splendens
Centrolophidae
Hyperoglyphe antarctica
Centrolophidae
Hyperoglyphe perciformis
Channichthyidae
Champsocephalus gunnari
Emmelichthyidae
Plagiogeneion
rubiginosum
Epigonidae
Epigonus telescopus
Lotidae
Molva dypterygia
Macrouridae
Coryphaenoides rupestris
Macrouridae
Macrourus berglax
Nototheniidae
Dissostichus eleginoides
Nototheniidae
Dissostichus mawsoni
Oreosomatidae
Allocyttus niger
Oreosomatidae
Pseudocyttus maculatus
Pentacerotidae
Pseudopentaceros
richardsoni
Pentacerotidae
Pseudopentaceros
wheeleri
Pleuronectidae
Reinhardtius
hippoglossoides
Polyprionidae
Polyprion americanus
Polyprionidae
Polyprion oxygeneios
Sebastidae
Sebastes fasciatus
Sebastidae
Sebastes marinus
Sebastidae
Sebastes mentella
Sebastidae
Sebastes proriger
Serranidae
Caprodon longimanus
Trachichthyidae
Hoplostethus atlanticus
Trichiuridae
Aphanopus carbo
Trichiuridae
Lepidopus caudatus
Non deep-sea fish examples
Clupeidae
Clupea harengus harengus
Engraulidae
Engraulis ringens
Gadidae
Gadus morhua
Rajiidae
Raja clavata
Sciaenidae
Larimichthys polyactis
Scombridae
Scomber japonicus
Serranidae
Plectropomus leopardus
Sphyrnidae
Sphyrna lewini
Squalidae
Squalus acanthias
Lmax (cm)
rmax
(year 1)
Max age
(year)
Intrinsic
vulnerability
index
0.23
0.24
1.09
0.16
–
–
8
57
67
58
24
71
118
104
110
43
21
91
39
130
131
303
0.42
0.12
0.59
0.6
1.38
0.44
0.20
0.17
0.23
0.21
21
73
15
–
–
20
45
54
39
–
68
78
57
45
23
61
60
82
80
84
Sablefish
Splendid alfonsino
Bluenose warehou
Barrelfish
Mackerel icefish
Rubyfish
120
70
140
91
66
60
0.08
0.52
0.15
0.11
0.45
0.88
114
17
60
85
–
10
82
62
85
58
56
41
Black cardinal fish
Blue ling
Roundnose grenadier
Roughhead grenadier
Patagonian toothfish
Antarctic toothfish
Black oreo
Smooth oreo dory
Pelagic armourhead
75
155
110
110
215
175
47
68
56
0.09
0.38
0.17
0.12
0.17
0.29
0.06
0.09
0.81
100
–
54
–
50
31
153
100
74
75
78
75
85
86
69
73
43
93
47.4
16.4
68
Slender armourhead
44
0.8
11
65
Greenland halibut
80
0.3
30
69
Wreckfish
Hapuka
Acadian redfish
Ocean perch
Deepwater redfish
Redstripe rockfish
Pink maomao
Orange roughy
Black scabbardfish
Silver scabbardfish
210
150
30
100
58
61
50
75
110
210
0.3
0.15
0.3
0.15
0.12
0.16
–
0.06
0.33
0.9
60
75
55
–
149
–
–
80
87
48
77
70
70
34
73
70
58
Atlantic herring
Peruvian anchoveta
Atlantic cod
Thornback ray
Small yellow croaker
Chub mackerel
Leopard coral grouper
Scalloped hammerhead
Spiny dogfish
55
24
200
120
40
64
146
430
160
0.45
3.00
0.40
0.80
1.70
0.55
0.38
0.29
0.14
22
3
25
12
7
18
26
35
75
30
39
68
53
30
46
46
82
87
where M (the natural mortality rate) is estimated from Hoenig’s
[62] empirical equation based on observed maximum age. If no
maximum age was known, the authors used the von Bertalanffy
growth parameter K and followed Jensen’s [63] suggested approximation with M¼3/2K.
60
Table 1 generally suggests that very low resilience/productivity (i.e. high vulnerability) is typical of deep-sea fishes, including
species that are commonly exploited by deep-sea fisheries.
The estimated rmax of the deep-sea species the authors
studied has a mean value of less than 0.37 year 1, with high
E.A. Norse et al. / Marine Policy 36 (2012) 307–320
intrinsic vulnerability (i.e., index460). Similarly, species commonly exploited by deep-sea fisheries have low average rmax of
0.314 year 1. Further, these have markedly lower rmax and higher
intrinsic vulnerability index than non-deep-sea fishes (i.e., species
generally found shallower than 200 m) of similar length (Fig. 2).
This agrees with results from previous assessments that deep-sea
demersal fishes, particularly those that aggregate around seamounts, are more vulnerable than other fishes [24,28]. Maximum
body size alone may not be a good indicator of resilience or
vulnerability to fishing because some of the highly vulnerable
species are not large.
These metrics of resilience and intrinsic vulnerability, specifically rmax, can be compared to economic metrics to evaluate the
sustainability of deep-sea fishing. In species where recruitment is
more or less stable at population sizes above 50% of unexploited
size, a reasonable assumption for many low-productivity species,
the maximum intrinsic growth rate rmax ¼ 2M, where M is the
natural mortality rate. This leads to a target fishing mortality rate
for maximum sustainable yield (MSY) of Fmsy ¼M. For species that
have maximum ages of 30 years or greater, M is expected to
beo0.1; thus, maximum fishing mortality rates under standard
management models must also be o0.1, a difficult target to meet
in open-access fisheries. If a local stock or population is depleted
(FbFmsy) and does not receive significant recruitment from
unexploited sources, the chances of local extinction are extremely
high.
1.5
Non deep-sea fish
Deep-sea fish
1.0
0.5
Species with restricted geographic range and aggregation
behavior are particularly vulnerable to overfishing [46,55,64].
Many deep-sea fishes that inhabit seamounts naturally aggregate
for feeding and spawning. These species include orange roughy,
splendid alfonsino (Beryx splendens), alfonsino (Beryx decadactylus,
Berycidae), blue ling (Molva dypterigia, Lotidae) and slender
armourhead (Pseudopentaceros wheeleri, Pentacerotidae). The level
of population connectivity among seamounts is unknown for most
species but recolonization rates may be very low or episodic [43].
This further reduces their resilience to fishing [24].
5. Principal vs. interest as a fishery concept
With a million dollars capital (¼ principal) in the bank, one can
withdraw $30,000 per year in perpetuity at a guaranteed 3% annual
interest rate. Likewise, many stocks (equities) generate dividends,
albeit more variably. Similarly, a fish biomass of one million kilograms that grows at an average rate of 3% per year will deliver, on
average, 30,000 kg of fish per year in perpetuity. At a price of $1/kg,
that will provide gross revenues of $30,000 per annum through time.
The foregoing illustrates how the economic concepts of capital
and interest are closely related to the biological concepts of
population (stock) biomass and annual growth rate of fish. Assuming that there is neither net population compensation nor depensation – the null hypothesis unless there is adequately supported
reasoning or metanalysis to indicate otherwise – depleting fishery
resources ‘‘eats up’’ our fish capital, thereby reducing the interest
(¼usable productivity) it generates and undermining its capacity
to benefit present and future generations [65].
Sustainability, therefore, is living off the interest that capital
generates ( ¼the surplus production that a fish stock generates).
Withdrawing too much capital from a bank account and depleting
fish stocks only decrease the interest (revenue) the stock will
generate in the future.
6. Productivity and interest rates determine prospects for
sustainability
0.0
6 - 44.9
45 - 299
Maximum length (cm, TL)
>= 300
90
Non deep-sea fish
80
311
Deep-sea fish
70
60
50
40
30
20
6 - 44.9
45 - 299
Maximum length (cm, TL)
>= 300
Fig. 2. The calculated (a) rmax and (b) intrinsic vulnerability index of non deep-sea
(gray bars) and deep-sea (open bar) fishes. The error bars represent 95%
confidence limits. Numbers of deep-sea fishes with available data to estimate
rmax and intrinsic vulnerability index are too small to calculate meaningful
confidence limits (N¼ 42 spp.) while the sample size for shallow water fishes is:
6–44.9 cm (N ¼ 215 spp.), 45–299 cm (N ¼394 spp.) and 4 ¼ 300 cm (N¼ 29 spp.).
The problems of overfishing can be split into two, the first
being about open access and competitiveness, the second being
that, even under sole ownership, the ocean can be emptied of
fishes whose intrinsic growth rate is lower than the discount rate
( ¼prevailing market rate).
It has long been known in economic theory [66–69] that open
access to a natural resource usually leads to overexploitation
because no single individual has an incentive for conservation
(the first problem). This is the so-called tragedy of the commons
[67]: The fish that I throw back into the sea will just be caught by
someone else. However, Clark [20,21] showed that even a private
sole owner who is the only one to fish may still have an economic
incentive to drive the stock to extinction (the second problem)
because, once a fishery is no longer a subsistence activity, but an
industry, it must compete with other uses for capital. To take the
analogy of the previous section, if the rate of return in other
competing industries is 5%, then the rate of return in the fishing
industry has to be 5%, even if it means eating into the fish capital,
eventually withdrawing it down to zero.
To be specific, suppose the growth rate F(x) of the fish stock is
given in terms of the stock x by a simple logistic equation
FðxÞ ¼ rx½1x=K
where r is the intrinsic growth rate of the resource and K is its
carrying capacity. Now let i be the expected rate of return from the
fishery. Colin Clark showed that if i4r, that is, if money grows faster
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E.A. Norse et al. / Marine Policy 36 (2012) 307–320
in the bank than fish in the sea, it is economically preferable, even
for a sole owner, to liquidate the fish stocks and convert them into
capital, thereby driving the fish stock to extinction. For deep-sea
fishes, where productivity is very low, the effect is very pronounced.
7. Sustainability and spatial patterns of deep-sea fishing
Around the world, including in the deep sea, many fisheries
are unmanaged or minimally managed. But for ones that are
managed, the most commonly used methodology – stock assessment – does not incorporate spatial patterning of fish and fisheries. Diversity of life histories among populations of a species can
be a major factor favoring non-declining catches [70]. Whether
unmanaged or managed, failure to account for spatial heterogeneity of fishes is likely a major reason for the growing incidence
of fishery collapses around the world [71], which the authors
summarize for the deep sea in sections to follow.
The assumption that targeted fish species move around randomly, so that fishing pressure in any one place within the boundary
of a fishery has the same impact as in any other, urgently needs to be
revised, particularly in the deep sea. A model that better explains the
serial depletion we see around the world comes from Berkes et al.
[68]: A fishing operation locates a profitable resource patch, fishes it
to unprofitability, then moves on, repeating this sequence until there
are no more profitable patches to exploit, at which point the fishery
is commercially (probably ecologically, and conceivably biologically)
extinct. Fishing does not deplete fish populations uniformly throughout a fishery’s spatial footprint. Rather, it is a patch-dynamic, mosaic
process that takes ‘‘bites’’ out of marine ecosystems. If these bites
deplete fish faster than they can regenerate, pushing them below the
threshold of profitability, then the bites coalesce until there are no
more patches of fish to be taken profitably.
This model has particular resonance in the deep sea. One
reason is that deep-sea fishing vessels are generally larger, and
therefore take bigger bites in any given fishing location, where
new technologies allow people to locate and fish for biomass
concentrations in areas that were until very recently hidden,
inaccessible or too expensive to fish. The other is that deep-sea
fish are so slow to recover from increased mortality.
Indeed, serial depletion is almost inevitable because – as Clark [20]
observed in whales, which, like deep-sea fishes are slow-growing – it
is economically rational behavior to reduce each stock to unprofitability until no more can be taken, then reinvest the capital (now in
the form of money) to obtain higher return on investment. And when
catch statistics are aggregated over large areas, this serial depletion in
a mosaic spatial pattern is obscured and difficult to detect, with each
as-yet unexploited patch giving the false impression of sustainability
as it is found, depleted and abandoned by fishermen who move on,
repeating the process.
The ‘‘roving bandits’’ Berkes et al. [68] describe are therefore
the spatial causal driver for Clark’s Law in the deep sea. By
creating the illusion of sustainable catches while serially depleting patches in the fish stock mosaic, deep-sea fishing more closely
resembles a Ponzi scheme than a sustainable activity. This bodes
poorly for both deep-sea fishes and the future of their fisheries.
The following sections provide spatially explicit longitudinal
examples of deep-sea fisheries that shed light on this process.
8. Evidence for sustainability in deep-sea fisheries
8.1. Elasmobranchs
Deep-sea elasmobranch fishes are targeted directly, primarily
for shark liver-oil, and are bycatch in fisheries targeting teleosts
and crustaceans. The low productivity of deep-sea elasmobranchs,
many of which are poorly known taxonomically and whose
population status is data-deficient, is a growing concern. Their
inability to sustain fishing pressure has led experts to conclude
that deep-sea elasmobranchs in general (not only larger species)
are very vulnerable to overexploitation [64,72,73]. Several papers
document the very low fishing mortality levels needed to overexploit deep-sea sharks [9,74,75]. Depth gives them no refuge;
deep-sea fisheries have already reached the maximum depths
attainable by elasmobranchs [76].
Demographic data compiled by the IUCN Shark Specialist
Group found suitable information for only 13 species (2.2%) of
deep-sea chondrichthyans [73]. rmax for these deep-sea species
falls at the lower end of the productivity scale for elasmobranchs,
making these among the lowest observed for any species. Population doubling times suggest recovery following exploitation will
take decades to centuries. Moreover, there is a significant decline
in the resilience of species with increasing maximum depth [73].
Whereas elasmobranchs are inherently vulnerable to overexploitation, deeper-dwelling ones are most vulnerable of all.
Harrisson’s dogfish (Centrophorus harrissoni, Centrophoridae)
illustrates this. An endemic dogfish from Australia, it declined more
than 99% from 1976–77 to 1996–1997 in waters of New South
Wales, according to fishery-independent trawl surveys [74]. This
species occupies a relatively narrow band of the continental slope,
and like other Centrophorus species, is believed to be among the most
biologically vulnerable of all sharks, with low fecundity (1–2 pups
every 1–2 years), high longevity (in some cases at least 46 years) and
probable late age at maturity [77]. IUCN now lists Harrison’s dogfish
as critically endangered. Unlike many other sharks, its decline was
noted by research surveys. This highlights a common pattern around
the world: Multi-species fisheries can threaten sharks [78] much
faster than regulators act to mitigate their decline.
The leafscale gulper shark (Centrophorus squamosus) is
targeted for its liver oil, often as part of multi-species demersal
fisheries. It matures late, has only 5–8 pups per year and lives to
be 70 years old [79]. In the North Atlantic, landings peaked in
1986 and have declined steadily since then. Further confounding
matters are reporting problems: Landings of this species are often
aggregated with a closely related species, and over large areas.
Little differentiates these two sharks from other deep-sea
elasmobranchs except for the availability of catch and demographic data. It is likely that other deep-sea elasmobranchs show
similar patterns.
8.2. Orange roughy
Orange roughy is a deepwater demersal species with an almost
global distribution. It inhabits continental slopes and seamounts
from 500–1500 m depths. It is slow-growing and reaches ages
exceeding 100 years. Natural mortality in adults is low (estimated
at 0.045 year 1 off New Zealand), they mature late (at about
30 years), their fecundity is low relative to most teleost species,
and adults do not spawn every year. These characteristics make
orange roughy much less productive than most shallower-living
commercially fished species.
Fishing for orange roughy started in New Zealand waters in the
late 1970s. Subsequently other fisheries developed off southeastern Australia in the late 1980s, in the North Atlantic in
1989, off Namibia in 1995, off Chile in 1998 and in the southwest
Indian Ocean (SWIO) in 1999 [80].
New Zealand catches rose steadily through the 1980s as new
populations were discovered, and when the Australian fishery
found spawning fish off St Helens Seamount, global catches
skyrocketed to over 100,000 t (Fig. 3). Numerous new fisheries
followed in the 1990s and early 2000s, the largest occurring
E.A. Norse et al. / Marine Policy 36 (2012) 307–320
313
Orange roughy stocks in New Zealand and Australia have
generally continued to decline even when catch has been reduced
to levels thought to be sustainable. Stock assessments are often
highly uncertain, partly because biological knowledge is lacking to
make the population models ecologically realistic. Several
New Zealand stock assessments have suggested that there may have
been several decades of below-average recruitment for some orange
roughy populations [82]. Lack of knowledge of recruitment is one of
the main concerns about the sustainability of these fisheries [11,90].
off Namibia and SWIO. The New Zealand fishery has dominated
global catches, and is the only one that has persisted over time
with total catches of more than a few thousand tonnes. Much of
this comes from a restricted area of the Chatham Rise east of the
main New Zealand islands [81]. Stocks in most other fishing
grounds around New Zealand have declined substantially [82],
and mirror the global pattern on a smaller spatial scale. Serial
depletion has occurred in some of the seamount-based fisheries,
and a number of areas are now closed (Fig. 4).
The Australian fishery was very large between 1989 and 1993
when catch rates of spawning fish on St. Helens Seamount were
high, but the stocks were rapidly depleted and quotas were
progressively reduced [83]. The St. Helens fishery is now closed
completely and Australia declared orange roughy a ‘‘threatened
species’’ in 2006. A similar situation occurred off Namibia and
Chile [84–86], where, despite extensive research and precautionary management objectives, catches could not be sustained, and
fisheries are now very small or orange roughy are just bycatch.
Similarly, in SWIO, large catches were taken for a short time, with
uncontrolled increase in effort in the early 2000s with no
management on the high seas, then a sharp drop in catches and
catch rates [87].
Sissenwine and Mace [18] noted two patterns in these catch
histories. In the first, small stocks were fished down rapidly
before effective management could be implemented. In the
second, with larger stocks, research initially overestimated stock
size, often coupled with non-conservative management practises
and ‘‘fishing-down’’ phases, which led to excessive depletion.
Francis and Clark [82] and Clark [88] have further examined
sustainability issues with orange roughy, and attributed overexploitation to a combination of biological characteristics and
habitat/fishery factors whereby their aggregation behavior makes
them vulnerable to rapid depletion, and research-management
limitations that mean often too little is learnt too late. Economic
considerations have also been important, as the market value for
orange roughy has historically been high, creating an economic
incentive for fishers to target the species [89].
8.3. Slender (pelagic) armourhead
There are three species of armourhead: slender (Pseudopentaceros wheeleri), pelagic (P. richardsoni) and longfin (P. pectoralis).
P. wheeleri, then commonly (if erroneously) called ‘‘pelagic’’
armourhead, was the target of large fisheries in the North Pacific.
Slender armourhead are relatively short-lived (11 years) and fastgrowing compared to orange roughy. They spend several years as
Catch (thousand t)
250
200
150
100
50
0
1975
1970
1980
1985 1990
Year
1995
2000
2005
Fig. 4. Catches of slender armourhead (dark gray) and alfonsino (light gray) from
Emperor and Hawaiian seamounts [80,133,148]. Splendid alfonsino image:
wikepedia.org.
120
Ireland
SWIO
Australia
Chile
100
N. Atlantic
Catch (thousand t)
Namibia
Australia
80
TasmanSea
NewZealand
60
N. Atlantic
40
SWIO
Namibia
NewZealand
20
Ireland
Chile
TasmanSea
08
20
06
04
20
02
20
00
20
20
98
96
19
19
2
94
19
19
9
19
90
19
88
84
19
86
19
0
19
82
19
8
19
7
8
0
Year
Fig. 3. Estimated catches of orange roughy in the major global fishing areas from 1978 to 2008. (Various data sources, authors’ unpublished records, FAO Statistics, ICES
reports, NZ Plenary reports).
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E.A. Norse et al. / Marine Policy 36 (2012) 307–320
pelagic fish migrating over large areas of the North Pacific before
becoming demersal and aggregating on seamounts to spawn
during the last years of their lives [91].
In 1967, Soviet trawlers discovered large aggregations on
seamounts in the southern Emperor Seamount Chain [80,92]. The
Soviet fleet caught up to 130,000 t a year in the early stages of the
fishery [80]. Most catches were taken on four seamounts at depths
between 300 and 600 m. Effort in the early years was very high,
with 18,000 Soviet trawler-days between 1969 and 1975 [92].
Stock size initially was estimated at between 240,000 and
350,000 t [93]. Large Japanese trawlers joined the fishery in 1969,
and combined catches of the two fleets peaked at about 180,000 t
in 1973, before dropping rapidly. Japanese catch per unit effort
decreased from a peak of 54 t h 1 in 1972 to less than 1 t h 1 from
1978. They switched to targeting alfonsino on the seamounts,
although, by 1982, both fisheries had become small [91]. Nonetheless, some Japanese fishing continued for alfonsino during the
1980s–90s, with annual catches typically 1000 to 6000 t. Catches
of armourhead were generally small, but in 1992 and 1993 and
again in 2004 larger catches over 10,000 t were taken.
Hence, although the armourhead stock was heavily overfished
during the 1960–1980s, it has recovered somewhat, with apparent pulses of recruitment contributing to the improved catches.
However, the stock has not recovered to anywhere near its
earlier size.
8.4. Grenadiers
There are almost 400 species of grenadiers [94] but only a
handful in the genera Coryphaenoides, Macrourus and Albatrossia
are of adequate size, habit and occurrence to qualify as the target of
a fishery. The many species of Coryphaenoides occur from the upper
slope to abyssal plain depths in all oceans. The four species of
Macrourus occur on the slope in high latitudes of the North Atlantic
and Southern Oceans. The single species of Albatrossia (the giant
grenadier, A. pectoralis) occurs on slopes across the North Pacific.
Roundnose grenadier (Coryphaenoides rupestris) and roughhead grenadier (Macrourus berglax) have been fished to nearexhaustion in the Northwest Atlantic [94]. The C. rupestris fishery
began in 1965 shortly after the former Soviet Union found
commercially fishable populations, peaked at 83,964 t in 1971,
crashed and never recovered until it ceased under moratorium in
1992. The fishery began off northern Labrador and swept through
the range and local populations were depleted, concluding off
southern New England. In 2008, the Committee on the Status of
Endangered Wildlife in Canada (COSEWIC) placed C. rupestris on
its list of endangered species. The fishery moved to the Northeast
Atlantic but appears to have peaked there in 2004 at 30,000 t. As
C. rupestris landings diminished, the focus shifted to M. berglax.
Never as large a fishery, it peaked at near 9000 t in 2000 in the
Northwest Atlantic. Stock assessments show that the population
has declined 88%. Bycatch of Macrourus throughout the Southern
Ocean is not inconsiderable and a targeted fishery is very possible.
Some fishery scientists believe there could be a viable fishery
in the Northwest Pacific for the lightly exploited giant grenadier
and popeye grenadier (C. cinereus) [94]. These are undoubtedly
abundant on the upper slopes across the region, but there are no
historical data and what little demographic information exists is
inadequate to determine how populations might respond to
exploitation. Because of the particular bioenergetic characteristics
of grenadiers, models derived for shallow-water species cannot be
used even if appropriate data were available. Initial overfishing
can have very long-term effects, as has been shown for C. rupestris
and M. berglax, and studies based on these two species show that
recovery time, even with a modest level of fishing, can be on the
order of centuries [29].
8.5. Black scabbardfish
In some cases, deep-sea fishes have been targeted for more
than a century, mainly around oceanic islands with steep slopes
[95]. These fisheries are typically labor-intensive and use handlines or longlines from small boats. The Madeira traditional
deepwater fishery is one of the more longstanding examples.
It probably started in the early 1800s when local fisherman
targeting squalid sharks between 600 and 800 m depth for oil to
light their homes accidentally caught black scabbardfish (Aphanopus carbo, Trichiuridae) [96,97]. Its quality and flavor quickly
made this fish the ‘‘trusty friend for poor local communities’’ [96]
and an important fishery for Madeira Island.
This fishery changed little until 1982, when monofilament
drifting longlines replaced hemp lines and hooks per line
increased [98]. This gear change, along with better equipped
boats, helped local fisherman searching for new fishing grounds
to increase catches from about 1000 t in 1982 to 3000 t in 1992
[98]. Black scabbardfish are now fished between 800 and 1200 m
on slopes of islands and seamounts [97].
This species may show fast growth for a deep-sea fish,
maturing at about 3 to 4 years and with longevity of 12–24 years
[99,100], which could help to explain its apparent sustainability.
Another reason is that the fishery used hook and line gear [101].
In the past, the complexity of Madeira’s seafloor prevented
bottom trawling. Now that trawlers can fish on steep slopes, the
Portuguese government and regional authorities have prohibited
use of trawls in both Madeira and the Azores. This became an EC
regulation (EC Reg. 1568/2005) under the new Common Fisheries
Policy to foster conservation of sensitive deep-sea habitats and
species [102].
Black scabbardfish fisheries are still artisanal in Portugal but
are much more industrialized elsewhere (e.g., French deepwater
freezer trawler fisheries in northern European waters) [103],
where CPUE shows a population decline [104]. For this reason,
the international Council for the Exploration of the Sea (ICES) has
asked for significant reductions in fishing effort. Present landings
in northern Europe are probably maintained by serial exploitation
of new fishing grounds. But in waters between the Azores and the
Canary Islands, artisanal longline black scabbardfish fisheries
seem to have stable catches and biomass, and may remain so if
fishing effort does not increase [104].
8.6. Other bony fishes
A number of other deep-sea teleosts are targets of major
commercial fisheries in various parts of the world. These include
alfonsinos (B. splendens and B. decadactylus, Berycidae), oreos
(in particular smooth oreo dory (Pseudocyttus maculatus) and
black oreo (Allocyttus niger, Oreosomatidae), toothfishes (Patagonian toothfish, Dissostichus eleginoides and Antarctic toothfish,
D. mawsoni, Nototheniidae), sablefish (Anoplopoma fimbria, Anoplopomatidae), blue ling (Molva dypterigia), cusk (Brosme brosme,
Lotidae) and wolffishes (Anarhichas spp., Anarhichiadidae). Oreos
are long-lived and slow-growing like orange roughy, but the other
species are more like typical shallow-dwelling species.
Catch histories of these fisheries show differing trends, but the
current catch levels of all are markedly lower than historical
maxima (Table 2). Decreases in catch result from a combination of
overfishing, a trend in some areas towards longlining rather than
trawling (e.g. trawling became more limited under the Convention on the Conservation of Antarctic Marine Living Resources
(CCAMLR) for D. eleginoides, and was prohibited from the beginning for D. mawsoni in the Ross Sea), and improved management
through catch reductions.
E.A. Norse et al. / Marine Policy 36 (2012) 307–320
Table 2
Recent (2007) reported catch by species relative to the historical maximum [146].
Species
Maximum
reported
catch (t)
Year of
maximum
catch
2007
reported
catch (t)
2007 catch as
percentage of
maximum catch
Toothfishes
Alfonsinos
Oreos
Sablefish
Blue ling
Wolffishes
Cusk
44,200
14,200
46,600
64,900
36,800
26,000
55,600
1995
2003
1981
1972
1980
1979
1980
24,700
6900
17,800
27,100
8200
2000
26,900
56
49
38
42
22
8
48
While catch levels overall can appear relatively stable, a
number of species have undergone such regional declines that
their fisheries have collapsed. Alfonsino fisheries off the Azores
and Corner Rise seamounts in the 1970s by the former Soviet
Union lasted only a few years, and a spawning location for blue
ling in the North Atlantic yielded 8000 t in one year before ceasing
as catches dropped rapidly [80]. In the western North Atlantic, the
three species of wolffish, and cusk, have reported declines in stock
size of over 90% within the time period of three generations, and
38% of deep-sea bottom fish species in that area could be ‘‘at-risk’’
based on the extent of population declines in surveys [29].
Yet off New Zealand, oreo fisheries have had relatively stable
landings for an extended period, and current stock status for both
major commercial species is estimated to be around 50% of
unfished levels [36]. Hence, fisheries can be sustained where life
history characteristics are known and appropriate management is
applied to limit catches and/or effort levels.
8.7. Deep-sea corals
Precious corals are caught in some deep-sea fishing operations.
They have been sought for use as adornments for millennia in
Mediterranean countries. Today, black, pink/red and gold corals
(Antipathidae, Corallidae and Zoanthidae) are collected for the
jewelry trade in the Mediterranean, India, Japan, Pacific Islands,
Hawaii and the Caribbean. In the Pacific Island region, collecting is
generally done selectively using scuba or submersibles, and the
precious coral ‘‘beds’’ are protected from overfishing [105,106],
though lack of profitability has halted this fishery in recent years.
Deep-sea corals are also landed in large quantities as
unwanted bycatch in other fisheries [107–109]. For example,
between 1990 and 2002, Alaskan fisheries, primarily in the
Aleutian Islands, landed approximately 4186 t of corals and
sponges, with 90% removed by bottom trawling [110]. In British
Columbia, between 1996 and 2002, at least 15 hauls took over 4 t
apiece. Orange roughy trawling on the South Tasman Rise
seamounts (adjacent to the Australia EEZ) landed 1.6 t of coral
per hour during the first year of the fishery (1997–1998). Indeed,
in the first year they took over 1100 t of corals, a coral bycatch
about 25% of the orange roughy catch [107]. Coral bycatch is
highest when trawling moves into a previously unfished area,
then rapidly declines. From a conservation perspective, therefore,
reduced coral bycatch is not necessarily a good sign.
Although short-term effects of bottom trawling are now
widely known [111–113], there have been limited studies on
long-term impacts [114]. Estimated recovery rates depend on the
life history of a particular organism, and range from one to five
times their generation time [115]. Deep-sea corals are slowgrowing and can be extremely long-lived [116], more than 4000
years for some colonies [117,118, which makes them exceedingly
vulnerable to overexploitation. The benthos on seamounts closed
to fishing have shown no signs of appreciable recovery from the
impacts of bottom trawling even after 10 years of closure [119].
315
For these deep-sea biogenic habitats, recovery is therefore likely
to take centuries or more [120].
In recent years, Australia, New Zealand, USA, Norway, UK and
Portugal have established large trawl closures to protect seafloor
ecosystems. There are also efforts to limit bottom trawling on the
high seas, including closures in the North and South Atlantic
[108,121].
9. Biomass, productivity, their economic analogs and
sustainability
Some resources are nonrenewable: When people exploit them,
they don’t regenerate. As humans deplete nonrenewable capital
stocks, our survival and prosperity therefore depend increasingly
on renewable ones. But some renewable resources have such low
resilience that our consumption essentially makes them nonrenewable, at least over time scales of human lifetimes. The lower
their productivity or resilience, the more important it is for people
to exercise self-restraint because resource biomass and productivity drive economics that, in turn, are crucial to the prospects for
sustainability.
One can gage prospects for sustainable use of renewable
resources with a simple 2 2 table (Table 3). Its two dimensions
are related because a fish stock’s biomass generates production of
new biomass, just as capital generates interest or dividends. But
biomass and productivity are also critically different. Species and
ecosystems occur in all four quadrants, and their position in these
quadrants determines economic incentives for human behaviors
that, in turn, determine prospects for sustainability.
Location, depth, biomass concentration (which all feed into the
cost of fishing) and per unit value all affect whether a population
is profitable or unprofitable to exploit, which largely determines
whether people want to extract a resource. As Sethi et al.
succinctly summarize, ‘‘Taxa with higher potential profit are
targeted first, followed by progressively less economically attractive alternatives [122].’’ Although deep-sea fishes are more
expensive to exploit, those having sufficiently high biomass
concentrations make tempting targets.
In the deep sea there are some areas where biomass density,
hence potential catch per unit effort, is high. These generally occur
where currents advect food, usually zooplankton, from larger areas.
Such transported production is filtered by seamount invertebrates
(e.g., corals) or captured by fishes such as orange roughy, which
hover near seamount crests. But these situations are unusual in the
deep sea; most high-biomass areas and fisheries have occurred
shallower, on continental shelves and in epipelagic upwelling
zones, where high productivity feeds the high yields of resources
that would be sustainable if only our fisheries were well-managed.
Whether a population can be sustainably fished is determined
by Clark’s Law. It can be interpreted, for all practical purposes, to
mean that people can only sustainably take living resources that
exceed a productivity threshold, the percentage of annual biomass
increment that exceeds prevailing annual interest rates. An insufficiently productive fish stock cannot, in practice, be exploited
Table 3
Suitability for commercial fisheries as a function of fish stock biomass and
productivity (¼ resilience).
Productivity
Biomass
Low
High
Low
High
Unprofitable
Unsustainable
Unprofitable
Suitable
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E.A. Norse et al. / Marine Policy 36 (2012) 307–320
sustainably because economics tempt us to liquidate it and
reinvest the capital gained thereby in investments paying higher
interest or dividend rates.
North American pines provide a clear non-fishery analog [123].
In the southeastern USA, loblolly pines (Pinus taeda, Pinaceae) on
warm, low-elevation sites with good rainfall are key resources for
the timber industry. They grow fast enough to log on 25–35 year
rotations; high resilience can make them sufficiently economically attractive to log sustainably. But some other species in the
same genus are much less productive, the extreme example being
bristlecone pines (P. longaeva) of eastern California. In their highelevation, nutrient-poor, cold, dry, windy environment (note
analogs to the deep sea), these exceedingly long-lived trees grow
crooked, making them unsuitable for saw timber, but their
weather-beaten beauty would nonetheless make them tempting
to cut. However, their annual biomass accumulation is exceedingly small, and recruitment is slow and episodic (like that of
deep-sea fishes such as orange roughy). As Clark’s Law explains, it
would be economically rational to log them all and reinvest the
proceeds, but that would be mining, not sustainable forestry.
Because low productivity makes P. longaeva so vulnerable, the US
government prohibits their logging [124].
More than 2500 years ago, Aesop’s fable The Goose that Laid the
Golden Eggs taught that greed destroys the source of good. High
biomass old-growth whales [20], trees [125] and deep-sea fishes
[82] all tempt us to overexploit. Ludwig et al. [126] recommended
that claims of sustainable ‘‘harvesting’’ should not be trusted.
Many nations have consciously made especially vulnerable
species, such as whales and giant trees, safe from exploitation.
But for reasons worth examining thoughtfully, fishes are treated
differently, by rules that owe less to Aesop than to Oscar Wilde,
who said ‘‘I can resist everything but temptation.’’
Large biomass concentrations of deep-sea fishes on some
seamounts and other limited areas cannot be sustainably
exploited because, even there, their productivity is generally too
low, much lower than for continental shelves where people
overfished so many fish stocks. These deep-sea biomass concentrations exist primarily because they had sufficient time for
occasional recruitment episodes to accumulate. But they do not
rebuild quickly or reliably, at least not within the time frame of
fisheries. Catches generally reduce biomass until the deep-sea
fishes cease being economically attractive. Thus, the centuries-old
analogy between cod fisheries and mines cited in this paper’s
introduction is even truer in the deep sea, where the interaction
of ecology (high biomass but low productivity/resilience) and
economics (the incentive to convert stock biomass to capital that
generates higher interest rates) compels fisheries to drive deepsea fish stocks down to uneconomic levels serially, mining the
deposits and moving on.
Now that fisheries have driven fish biomass and productivity
far below their potential in productive shallow waters near
fishing ports (the lower right quadrant of Table 3, the best places
to fish), humankind is now exploiting the last high-biomass oldgrowth fish concentrations in the deep sea (the lower left
quadrant, the worst places to fish). The great majority of deepsea fisheries are unsustainable unless governments consciously
choose to supersede the economically rational but destructive
incentives of Clark’s Law by instituting precautionary regulation.
In many cases, that likely means not fishing inherently vulnerable
populations and stringently enforcing such regulations.
Is low productivity in the overwhelming majority of deep-sea
fishes an inconvenient truth that fishery managers, countries,
Regional Fishery Management Organizations (RFMOs) and United
Nations bodies will choose to overlook? Can humans resist the
temptation of temporarily profitable concentrations of biomass
whose low productivity incentivizes us to fish unsustainably?
And can our institutions act before it is too late? The next two
sections of this paper are relevant to those questions.
10. Subsidies and sustainability
Deep-sea demersal fish species are more vulnerable to exploitation than the fishes whose depletion led to fishing farther from
land and into the deep sea. This is, in part, because low growth
rates relative to the available market discount rate for capital
make it desirable for fishermen to mine, rather than sustainably
exploit deep-sea fishes. That is true even in the absence of
fisheries subsidies [127]. But many governments actually increase
the economic incentive for doing this by subsidizing fish mining.
It is well-documented that almost all governments around the
world provide subsidies to their fishing industries [128–130].
Sumaila et al. [131] estimated that the fisheries subsidy to high
seas bottom trawling fleets, globally, is about US $162 million per
year, which constitutes 25% of the total landed value of the fleet’s
catch. Economic data for bottom trawlers suggest that the profit
achieved by this vessel group is normally not more than 10% of
landed value. Hence, their worldwide contribution to economic
activity is limited.
The implication of this finding is that, without subsidies, most
of the world’s bottom trawl fleet operating in the high seas would
be operating at a loss and unable to fish, thereby reducing the
current threat to deep-sea and high seas fish stocks. It is also
worth nothing that the total catch by these fleets is less than 1% of
the tonnage or value of the global marine catch [108,131],
implying that they contribute next to nothing to global food
security.
11. The legal regime in the least protected place on Earth
The exceptional biological and economic vulnerability of many
deep-sea fish species, and subsidies to deep-sea fishing fleets, in
combination, make them exceptionally difficult to manage sustainably. Thus, any effective legal regime would have to ensure
that deep-sea fisheries are: (1) governed by highly precautionary
rules, (2) supported by adequate data and scientific information,
(3) established by a transparent management body, and (4) effectively implemented [132]. At present, none of these preconditions
are being met in most areas of the high seas [7,133], and only
rarely are they met within the EEZs of coastal states [134].
Within EEZs, only a handful of countries have a robust
scientific basis for making management recommendations, and
most lack transparent and participatory processes to convert
those recommendations into policy. Moreover, only 17% of coastal
states have the capacity for effective enforcement [134]. Nevertheless, within EEZs, governments have the legal authority (if not
always the capacity) to unilaterally improve management processes and to control access to fisheries. Thus, at least some deepsea fisheries should stand a chance of being sustainable. The black
scabbardfish fishery in Madeira is one – albeit rare – example.
However, most of the world’s deep-sea ecosystems are in
international waters (the high seas), where sustainability of
deep-sea fisheries hinges on a more complex web of interdependent actors, including flag states, port states, market states and
RFMOs governed by an unfinished legal regime [132,135].
Under international law, all states have the right for their nationals
to fish on the high seas (article 116) [136]. However, all states have a
reciprocal responsibility to manage and control their fishing vessels
and nationals on the high seas, and to cooperate to ensure conservation of living marine resources (articles 117–119) [136]. Under the
FAO Code of Conduct for Responsible Fisheries [137] and the UN Fish
E.A. Norse et al. / Marine Policy 36 (2012) 307–320
Stocks Agreement for straddling and highly migratory fish stocks
[138], these duties are further elaborated in terms of ecosystembased and precautionary management and the roles of RFMOs with
respect to the use of science, transparency and participation.
Unfortunately, as a result of lax flag state control, illegal,
unreported and unregulated (IUU) fishing persists [139,140].
Moreover, due to conflicts of interest within many RFMOs,
decisions to reduce catches of target stocks are made slowly,
scientific advice and ecosystem impacts are often ignored, and
even when strong measures are adopted, opt-out provisions can
enable major players to ignore the rules [140]. This is a recipe for
disaster in the deep.
The good news is that this deep-sea ‘‘tragedy of the commons’’
has been recognized, and actions to redress at least some of these
shortcomings are being put into place [141]. In 2006, the United
Nations General Assembly (UNGA) adopted a resolution on
‘‘Sustainable Fisheries’’ [142] calling on states to undertake an
explicit set of time-limited actions to ensure sustainability of
deep-sea fisheries on the high seas and to protect vulnerable
deep-sea ecosystems, consistent with the precautionary and
ecosystem approaches.
The UNGA also requested that FAO develop ‘‘Guidelines for the
management of deep-seas fisheries on the high seas.’’ These Guidelines, adopted in August 2008, call for rigorous management of deepsea fisheries throughout all stages of their development, and for
keeping catch rates low until knowledge, management capacity and
measures for monitoring, control and surveillance increase [143].
A review of progress in implementing the UNGA resolution in
late 2009 revealed that, while a number of RFMOs had adopted
measures such as closed areas to reduce the impact of fishing on
deep-sea habitats, few RFMOs had taken steps to ensure the
sustainability of deep-sea fisheries [144]. As a result, the UNGA
adopted a new resolution with clear language calling for States
and RFMOs not to authorize deep-sea fisheries unless an impact
assessment had been performed and measures adopted to prevent significant impacts on deep-sea ecosystems. It then explicitly
called for States and RFMOs, where scientific information is
uncertain, unreliable or inadequate, to ‘‘adopt precautionary management measures to ensure that fishing effort, capacity and catch
levels did not exceed levels consistent with the sustainability of the
fish stocks and non-target species.’’ [UNGA resolution 64/72, paragraph 119(d) (emphasis added) [142].
Improved adherence to the 2006 and 2009 UNGA resolutions
and FAO Guidelines could help towards achieving sustainability of
deep-sea fisheries. However, until states fully implement their
obligations, including through better flag state and RFMO performance, and better data, the preconditions for sustainability for
deep-sea fisheries on the high seas will not be met. And as
unlikely as that is in deep-sea portions of countries’ EEZs, it is
even less likely on the high seas under current conditions.
A UNGA review of progress by States and RFMOs in implementing
the 2006 and 2009 resolutions in late 2011 provides an opportunity for all States to insist that deep-sea fisheries on the high seas
be managed on a sustainable basis, or not allowed to proceed.
317
The surplus production of deep-sea fishes is generally low, but
their biomass can be attractively high. Large withdrawals of this
biological capital (high catch rates) in the early years of some
deep-sea fisheries have repeatedly misled the fishing industry
and resource managers into believing that deep-sea stocks can be
sustainably exploited. This belief is often endorsed by agencies
interested in the large economic returns that these fisheries
usually generate in their early years.
As Clark [11], Roberts [12] and Large et al. [14] observe, deepsea fishing is fish mining. Deep-sea fisheries exaggerate a general
feature of marine fisheries, the pernicious disconnect between the
natural spatiotemporal patterns of productivity of stocks and the
perceived need for continuous high catches that has fueled the
growth of the global fishing enterprise by serially depleting fish
stocks. The serial collapses that took 50 years in coastal marine
fisheries takes only 5–10 years in the deep sea. These fisheries
also often rely extensively on bottom trawling, and a sustainable
combination of low catches with limited ecosystem impact is a
difficult, almost impossible, balance to achieve [145].
Given the widespread subsidization of energy-intensive deepsea fisheries and the relatively tiny catches they generate globally,
there is a persuasive argument that the best policy would be to
shut these fisheries down and redirect subsidies currently allocated to them toward (1) compensating the impacted fishers and
(2) helping to rebuild fish populations in highly productive waters
closer to fishing ports and markets, places far more conducive to
sustainable fisheries. Those involved in deep-sea fisheries should
bear the burden of proving their sustainability if these fisheries
are to develop, or continue.
Ending deep-sea fisheries would be particularly appropriate
for the high seas outside the EEZs of maritime countries, where
fisheries from just a few countries are harming the biodiversity
that is a vital interest for all humankind.
Acknowledgments
The authors thank our colleagues Katie Holmes, Caley Anderson, Susanne Adamson, Liz Rauer, Fan Tsao, Jeff Ardron, John
Guinotte, Nathaniel Paull, Aja Peters-Mason, Stephen Lutz, Tse
Yang Lim, Martin Smith, Pippa Gravestock, Ransom Myers, Ellen
Pikitch, Beth Babcock, Matt Gianni, Murray Roberts, Tony Koslow,
Gilbert Rowe, Colin Simpfendorfer, Sarah Fowler, Claudine Gibson, Sarah Valenti, Peter Kyne, Susanna Fuller, Harlan Cohen,
Fikret Berkes, Alex Rogers, Graeme Kelleher, Gregor Cailliet and
Colin Clark, who provided essential data, images or references, or
read portions of the paper.
The authors are deeply grateful to the patient and supportive
Charlotte Hudson, Caroline Good and Margaret Bowman, who
saw the importance of an interdisciplinary synthesis of this scope.
Finally, all of us offer special thanks to the Lenfest Ocean
Program, which funded Marine Conservation Institute’s Sustainability of Deep-sea Fisheries Project and thus brought us together as
collaborators and coauthors, and The Pew Charitable Trusts, which
supports the University of British Columbia’s Sea Around Us, from
which much of this material was derived.
12. Conclusion
After briefly reviewing key aspects of the biology of deep-sea
fishes, the authors of this paper conclude that sustainable exploitation is feasible for very few of them under prevailing economic
conditions and governance arrangements. The authors do note
that catches of a handful of species can be or can give the
appearance of being sustained, primarily ones that (a) can occur
shallower than 200 m, (b) have relatively high population resilience and (c) are fished with low-tech, non-trawl methods.
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